**4. Optimized Partition of the PLES**

*4.1. Principles of Optimizing Zoning*

(1) Principle of ecological priority

Jiangjin District is located in the ecological barrier construction area on the upper reaches of the Yangtze River and at the end of the Three Gorges Reservoir. Furthermore, the ecological environment of Jiangjin District is relatively fragile, so ecological protection is a major task of Jiangjin District. Therefore, when zoning for space optimization, all the grids of the ES are classified as ecological conservation areas to protect the ecological environment of Jiangjin District.

#### (2) Principle of area dominance

There are bound to be multiple types of spatial combinations within each township. By comparing the area sizes of different spatial types, the spatial type with the largest area is used to determine the optimal spatial division type of each township.

(3) Principle of coordinated development

The essence of optimizing the territorial spatial pattern is to enhance the capacity of regional sustainable development through the optimization of the structure and distribution of the PLES and to provide a space guarantee for social development, livable life and good ecology. Due to the differences in the strengths and weaknesses of the PLEF in different spatial units, the weak functions should be promoted in the process of space optimization to achieve the goal of the coordinated development of the PLES.
